摘要:
A method of purifying alkoxysilanes contaminated by organosilicon compounds with hydrolyzable chlorine atoms is disclosed wherein the alkoxysilanes are reacted in a pressure reactor with an alcohol, preferably in the presence of an HCl acceptor, at a temperature of 5.degree. C. to 160.degree. C. above the boiling point of the alcohol used and at the pressure which develops in the reactor.
摘要:
Reactor for carrying out chemical and physical materials transformations, which comprises a reaction space enclosed by a reactor housing, where the reactor housing has at least two lateral fluid inlets having adjustably mounted nozzles which include an angle of about 20-160 degrees and through which fluid jets which impinge on one another at a common collision point within the reaction space are passed and the reactor has a fluid outlet at the bottom of the reaction space, which is characterized in that—an exchangeable bottom plate•which has a hole as fluid outlet and•on which moveably supported spheres are located so as to block the original path of the individual fluid jets in the unaligned state rests on the bottom of the reaction space and—a half shell standing upright on the bottom of the reaction space is located between each moveably supported sphere and the wall of the reactor space and—bottom plate, half shell and moveably supported spheres comprise one or more hard materials.
摘要:
An aqueous dispersion containing pyrogenically prepared oxide particles of titanium, zinc, iron or cerium with an average particle size, expressed as the median, in the dispersion of less than 250 nm, that the particle sizes of the oxide particles in the dispersion are not distributed symmetrically and the dispersion contains, as a dispersant, at least one compound of the formula (I) and/or a maleic anhydride/acrylate copolymer of the general formula (IIa) and/or a maleate/acrylate copolymer of the general formula (IIb). It is prepared by dispersing a predispersion stream by means of a high energy mill. It can be used in sunscreen formulations.
摘要:
An aqueous dispersion, having a silicon dioxide powder having a silicon dioxide content of 10 to 60 wt.%, wherein the aqueous dispersion is stable in the pH range of 2 to 6, the aqueous dispersion additionally contains at least one compound, which is at least partially soluble in aqueous solution in the pH range 2 to 6 in the form of polyvalent cations, these being stable in a silicate-like environment as an anionic component of the particle surface of the silicon dioxide powder, the quantity of cation-providing compound in relation to the surface of the silicon dioxide is 0.001 to 0.1 mg cation-providing compound/m2 silicon dioxide surface, the cation-providing compound being calculated as the oxide, and the zeta potential of the aqueous dispersion has values of less than or equal to zero.
摘要翻译:一种水分散体,其二氧化硅粉末的二氧化硅含量为10至60重量%,其中水分散体在pH范围为2至6时是稳定的,水分散体还含有至少一种化合物,其在 在多价阳离子形式的pH范围2〜6的水溶液中最少部分溶解,这些在作为二氧化硅粉末的粒子表面的阴离子成分的硅酸盐样环境中稳定,提供阳离子的化合物的量 相对于二氧化硅的表面为0.001〜0.1mg的提供阳离子的化合物/ m 2二氧化硅表面,阳离子提供化合物以氧化物计算,并且水溶液的ζ电位 色散的值小于或等于零。
摘要:
Process for the production of an aqueous dispersion of pyrogenically produced metal oxide and metalloid oxide powders with a BET surface area of between 5 and 600 m2/g, with a metal oxide or metalloid oxide content in the dispersion of between 5 and 25 wt. %, comprising the following steps: water, which is optionally adjusted to pH values of between 2 and 4 by adding acids, is circulated from a receiving vessel via a rotor/stator machine, and metal oxide or metalloid oxide powder is introduced, using a feed device, into the shear zone between the slots in the rotor teeth and the stator slots, continuously or discontinuously and with the rotor/stator machine running, in a quantity such that a predispersion with a solids content of between 20 and 40 wt. % results, and, after all the metal oxide powder or metalloid oxide powder has been added, the feed device closes and shearing continues in such a way that the shear rate is in the range of between 10000 and 40000 s−1, and then, by dilution, the predispersion is adjusted to the desired solids content of the dispersion while maintaining the dispersing conditions.
摘要:
An aqueous dispersion for use as a finishing agent for textiles, wherein the dispersion contains a pyrogenically produced, aggregated silicon dioxide powder and a cationic polymer which is soluble in the dispersion, wherein the cationic polymer is present in a quantity such that the particles of the silicon dioxide powder exhibit a positive zeta potential.
摘要:
Process for the production of an aqueous dispersion of pyrogenically produced metal oxide and metalloid oxide powders with a BET surface area of between 5 and 600 m2/g, with a metal oxide or metalloid oxide content in the dispersion of between 5 and 25 wt. %, comprising the following steps:water, which is optionally adjusted to pH values of between 2 and 4 by adding acids, is circulated from a receiving vessel via a rotor/stator machine, andmetal oxide or metalloid oxide powder is introduced, using a feed device, into the shear zone between the slots in the rotor teeth and the stator slots, continuously or discontinuously and with the rotor/stator machine running, in a quantity such that a predispersion with a solids content of between 20 and 40 wt. % results, and, after all the metal oxide powder or metalloid oxide powder has been added,the feed device closes and shearing continues in such a way that the shear rate is in the range of between 10000 and 40000 s−1, andthen, by dilution, the predispersion is adjusted to the desired solids content of the dispersion while maintaining the dispersing conditions.
摘要:
Aluminium oxide dispersion, which is stable in a pH range 5 from 5 to 9 and has an aluminium oxide content of at least 40 wt. %, obtainable by dispersing pyrogenically produced aluminium oxide particles in an aqueous phase, wherein one or several at least dibasic hydroxycarboxylic acids present dissolved in the dispersion and at least one salt of a 10 dialkali metal hydrogen phosphate and/or alkali metal dihydrogen phosphate are added to the aqueous phase each mutually independently in a quantity of 0.3−3×10−6 mol/m2 of aluminium oxide specific surface area.
摘要:
Aqueous dispersion obtainable by placing in water an aggregated titanium dioxide powder having a specific surface area of from 20 to 150 m2/g in such an amount that the desired dispersion comprises at least 20 wt. % titanium dioxide, and at least onc amino alcohol having from 1 to 6 carbon atoms, and at least one carboxylic acid from the group comprising dibasic carboxylic acids and/or hydroxycarboxylic acids having from 2 to 6 carbon atoms,—the amino alcohol being present in the dispersion in an amount of from 2.5 to 7.0 μmol./m2 specific surface area TiO2 and the carboxylic acid being present in an amount of from 1.0 to 3.5 μmol./m specific surface area TiO2,—producing a pre-dispersion by introducing energy in an amount of less than 200 kJ/m3 and then producing a dispersion in which the aggregated titanium dioxide powder has a mean, volume-related aggregate diameter of less than 150 nm by grinding the pre-dispersion by means of a high-energy mill at a pressure of at least 500 bar. The dispersion can be used in the coating of glass, ceramics and metal surfaces.
摘要翻译:通过将具有20至150m 2 / g比表面积的聚集二氧化钛粉末放入水中而得到的水分散体,其量使得所需分散体包含至少20wt。 %二氧化钛和至少具有1至6个碳原子的氨基醇,以及至少一种含有2至6个碳原子的二元羧酸和/或羟基羧酸的羧酸, - 存在的氨基醇 在分散体中的量为2.5-7.0μmol/ m 2 SO 3比表面积TiO 2和羧酸的存在量为1.0-3.5μmolol ./m比表面积TiO 2, - 通过引入少于200kJ / m 3的量的能量产生预分散,然后产生分散体,其中 通过在至少500巴的压力下通过高能研磨机研磨预分散体,聚集的二氧化钛粉末具有小于150nm的平均体积相关聚集体直径。 分散体可用于玻璃,陶瓷和金属表面的涂层。
摘要:
Process for the production of an aqueous dispersion of pyrogenically produced metal oxide and metalloid oxide powders with a BET surface area of between 5 and 600 m2/g, with a metal oxide or metalloid oxide content in the dispersion of between 5 and 25 wt. %, comprising the following steps:—water, which is optionally adjusted to pH values of between 2 and 4 by adding acids, is circulated from a receiving vessel via a rotor/stator machine, and—metal oxide or metalloid oxide powder is introduced, using a feed device, into the shear zone between the slots in the rotor teeth and the stator slots, continuously or discontinuously and with the rotor/stator machine running, in a quantity such that a predispersion with a solids content of between 20 and 40 wt. % results, and, after all the metal oxide powder or metalloid oxide powder has been added,—the feed device closes and shearing continues in such a way that the shear rate is in the range of between 10000 and 40000 s−1, and—then, by dilution, the predispersion is adjusted to the desired solids content of the dispersion while maintaining the dispersing conditions.